In the past, compositions of dithiocarbamate and phosphorous have been utilized as fungicides. For example, U.S. Pat. No. 4,698,334 to Horriere et al. and U.S. Pat. No. 4,806,445 to Horriere et al. propose fungicidal compositions based on alkyl phosphites in combination with various contact fungicides such as mancozeb. U.S. Pat. No. 4,139,616 to Ducret et al. describes fungicidal compositions based on alkyl phosphites. U.S. Pat. No. 5,336,661 to Lucas et al. and U.S. Pat. No. 5,665,672 to Lucas et al. describe fungicidal compositions based on monoester salts of phosphorous acid or alkyl phosphites and dithiocarbamates. None of these references describe compositions containing phosphite without alkyl substituents. Furthermore, none of these references describe the use of these compositions as fertilizers.
Water-dispersible granules of phosphite fungicial products have been described in the art. For example, U.S. Pat. No. 5,656,281 to Hytte et al. discloses concentrated fungicidal compositions with phosphite, dithiocarbamates and wetting agents or dispersing agents. All of the compositions in Hytte contain wetting agents or dispersing agents. Furthermore, Hytte does not describe the use of these compositions as fertilizers.
Phosphite has been known for its fertilizer properties since at least the 1990s through Lovatt (U.S. Pat. No. 5,514,200, which issued May 7, 1996; U.S. Pat. No. 5,830,255, which issued Nov. 3, 1998; U.S. Pat. No. 6,113,665, which issued Sep. 5, 2000; and U.S. Pat. No. 6,645,268 B2, which issued Nov. 11, 2003) (U.S. patent application Ser. No. 09/637,621, filed Aug. 11, 2000; Ser. No. 10/686,411, filed Oct. 14, 2003). Prior to this discovery, phosphite was relegated for use only as a fungicide (U.S. Pat. No. 4,075,324) and as a food preservative.
There still remains a need in the art for improved fertilizer and fungicide compositions that can efficiently provide phosphorous as well as other nutrients such as zinc and magnesium to a plant. These compositions should be easy to pour from a container and should be free of dispersants or wetting agents. The present invention fulfills this need, as well as others.